Many vehicles include a hoist apparatus for loading containers or other items onto the vehicle and for unloading the containers or other items therefrom. In particular, one such vehicle is known as a container handler or loaded container handler. Container handlers typically comprise a hoist apparatus carried on a wheeled chassis that is actuated by pressurized fluid selectively directed by manual controls. Conventionally, the hoist apparatus includes forks carried at the distal end of a lifting arm that are pivotable with respect to the lifting arm via a hydraulic cylinder. The lifting arm is usually pivotable or extendable toward and away from the vehicle chassis via one or more additional hydraulic cylinders. When the vehicle is at a stop, the lifting arm or boom and forks are manipulated to engage a container. The container is then elevated through coordinated movement of the lifting arm and forks to position the container on the chassis. Some container handling vehicles may contain a “hopper” over which the container can be positioned to deposit refuse in the hopper.
Another vehicle that includes a hoist apparatus is known as a “roll off” vehicle. Roll off vehicles generally include a vehicle body or trailer that is adapted to receive a container, such as a large refuse container, that is adapted to roll onto and off of the vehicle. Roll off vehicles often include a hoist apparatus including a sub-frame that is mountable to the vehicle body or trailer and a main-frame that is pivotally mounted to the sub-frame that extends along the vehicle body. The main-frame pivots upwardly relative to the sub-frame, again typically via a hydraulic cylinder, to create a ramp onto which a container can roll on or off. Commonly, the hoist apparatus includes a cable winch system for drawing the container up onto the main-frame during the loading of the container and for easing the container off of the main-frame during the unloading of the container. Typically, one or more pulleys or sheaves are utilized in connection with the operation of such cable winch system. Once the container is loaded onto the main-frame of the hoist apparatus, the main-frame may then be lowered, thereby loading the container onto the roll-off vehicle.
As noted above, hydraulic cylinders are typically used to actuate the hoist apparatus on container carriers, roll off vehicles, or other such vehicles. These hydraulic cylinders are typically operated by manual controls, such as levers or joysticks, located in the cab of such vehicles or located on a valve group mounted on the vehicle chassis. The levers are typically each configured as pneumatic control valves, whereby a supply of pressurized air is supplied to the levers and movement of the levers causes pressurized air to be transmitted through tubing to a pneumatic actuator on a hydraulic control valve. Air pressure acting on a mechanical actuator (such as a piston or diaphragm) causes a valve spool in the valve to change position, which in turn allows hydraulic fluid to flow to the hydraulic actuator. The flow of hydraulic fluid causes the hydraulic cylinder to operate, as is well known.